The subject embodiment pertains to the art of printing systems. More particularly, this disclosure relates to a system and method for synchronizing relative operating positions of photoreceptor belts within the printing assembly to avoid undesirable belt seam positioning that can diminish system throughput efficiency.
Electrophotography, a method of copying or printing documents, is performed by exposing a light image representation of a desired original image onto a substantially uniformly charged photoreceptor substrate, such as a photoreceptor belt. In response to this light image, the photoreceptor discharges to create an electrostatic latent image of the desired original image on the photoreceptor's surface. Developing material, or toner, is then deposited onto the latent image to form a developed image. The developed image is then transferred to an image receiving substrate. The surface of the photoreceptor is then cleaned to remove residual developing material and the surface as recharged by a charging device in preparation for the production of the next image.
For example, FIG. 1 schematically depicts the various components of one electro photographic printing/imaging system 10 for printing images on a continuous print web medium 12 or cut sheet substrate with the same print device. A similar system is shown, for example, in U.S. Pat. No. 6,909,516, U.S. Pat. No. 6,369,842, U.S. Pat. No. 5,970,304, U.S. Pat. No. 5,878,320, U.S. Pat. No. 5,875,383, U.S. Pat. No. 5,860,053, which are incorporated herein by reference in their entirety.
As shown schematically with dashed line outlines, a printer or imaging device 14 may optionally include a document sheet feeding and scanning module 15 and/or an integral/separate electronics input and/or network server module, as on the left side of printer 14. In this exemplary printer or print engine 14, a conventional single continuous belt photoreceptor 16 having a seam 16a is being sequentially imaged with latent images, such as by a ROS laser printing charging station 18, or an LED bar, or the like. Although not illustrated in detail, the seam 16a has a width and length, which may be different in dimension than illustrated in FIG. 1 depending upon the system, belt and/or construction. The latent images on the photoreceptor belt 16 are developed with visible image developer material (e.g., toner) by a development station 20, which may include multiple development units for multiple colors. At an image transfer station 22 the developed images are transferred from the photoreceptor 16 to one side of the image substrate or print web medium. In this particular example, the transfer station 22 is located near the downstream side of the printer 14, where the photoreceptor belt 16 is moving vertically upward.
Within the xerographic print engine 14, a conventional fusing station system 23 is provided, in which transferred developed images are permanently affixed or fused to the continuous print web medium 12 when the system 10 is in a continuous print web mode and to a cut-sheet print medium when in a cut-sheet mode. A fusing assembly of the fusing station 23 permanently affixes the transferred powder or toner, for example, via a heated fuser roller and a back-up roller with the powder image contacting the fuser roller. The printer 14 is controlled by a programmable controller 11 that can operate the scanning module 15, a web feed module 70 and/or a finisher module (not shown).
The web feed module 70 is provided for turning over the web 12 after one side 12a has been imaged at a first side, and fused in a first roll fuser 80, then returning the inverted web 12 in proper page sequence for its opposite, second, side 12b printing, in which additional transfer stations to the transfer station 22 having a transfer module 72a may be used. The web 12 path illustrated in FIG. 1 includes multiple rollers, such as a ninety degree web turn roller 78 to turn the web vertically into a first side web expandable loop 79 formed by an outer, first, 180 degree web turn roller 81, and a first side moving roll fuser 80, as well as other rollers for angling, transposing, and moving the web 12 up into a second side roll fuser 90, for example, for duplex printing.
Printing engines utilizing photoreceptor belts, as opposed to drums, have seams where two ends of the belt are fastened together to make an endless surface. Consequently, the seam prevents uninterrupted continuous imaging of the photoreceptor. Wasted resources, such as unused web (e.g., portions of a paper roll or other medium) often result from the seam. In addition, if used to store any image data, the seam can mar the output image or provide non-uniformity, particularly with continuous feed web input and output. Continuous web feed systems are well suited for disengaging the web from the photoreceptor belt, reversing web direction, reversing again, and re-engaging the web to synchronize with the photoreceptor belt, which is known as a “pilgrim step.” It is an operational objective that there is no delay in paper feed through such imaging systems so that throughput is consistently maximized.